From nobody Wed Dec 17 08:52:33 2025 Received: from submarine.notk.org (submarine.notk.org [62.210.214.84]) by smtp.subspace.kernel.org (Postfix) with ESMTP id CE7B0253351 for ; Wed, 19 Mar 2025 11:20:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=62.210.214.84 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742383243; cv=none; b=ItuOyGurkpv+PobNL8cdYBRHmpqmYJ78bvQn14ETs0Zr6AyrsGS/Nbb0DsgE3lYoG5n2M6V3Hd9Z8u09bwxYj5aiOQ6yZDuTdkt4FAI9l3AmdH0jn16DePnrSLEQm6n99gvy0prP3XdD2AyJ4PjlTSAPnBSe3bdEMfnvZx7XoFY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742383243; c=relaxed/simple; bh=3J58Se8XDTl9BlGgRs5d+IlBlOxSoL35kOrUGSCwDcM=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:To:Cc; b=cGfVxWwvtxUzcK1NAZRRFtyBzmdjDYrCNVvGTtfKrJ4rTOh46boDEhePjFjCve13uoi4x7p45vceBFY6lxUDtNVZVsJmsqtvaPucMhD8YInAFZ1BWAHeP+0SDcTkI5ZdNgLIAl8AYyRoTR5gJcjY/i8OvwtdF/TbuqCNOsjq9Oo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=codewreck.org; spf=pass smtp.mailfrom=codewreck.org; dkim=pass (2048-bit key) header.d=codewreck.org header.i=@codewreck.org header.b=JIWEf3xH; arc=none smtp.client-ip=62.210.214.84 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=codewreck.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=codewreck.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=codewreck.org header.i=@codewreck.org header.b="JIWEf3xH" Received: from gaia.codewreck.org (localhost [127.0.0.1]) by submarine.notk.org (Postfix) with ESMTPS id 8BCF914C2D3; Wed, 19 Mar 2025 12:20:31 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=codewreck.org; s=2; t=1742383233; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=lXpgVvCHByq70ntTWtHcQtsufg4U/O6aceBq0lCugzo=; b=JIWEf3xHy6HLfPcZIlPCTBJrwHhTuwPFgXkI/GHmE2gH9RHMNRh0EmG9zI97aKfeghRuPd oWIylvR+zhgWtwY8tPqWJm5labeLymHzTfzF+M1KFszHcnMmL8YzkedjiVf3uRCzZHmE8y jdGD5ih29L5UvjsUJG3i+lduNbDvVeR0SmPluroTBLvk9OZYb5dTF73YoFxzBg/SXQr/aO 2lYO9WtPRYeCAgICU1nCYjZ1RU1MJISerFLgnOA3o0gymE+ciWeaacP6ZA29Dr3K3TzZad NZ6nfCwWzF7c/xMYuiPAQLt3HypLpUMbuV9OhEBH4DyMs3hZXVDZtXCwghMOrg== Received: from [127.0.0.1] (localhost.lan [::1]) by gaia.codewreck.org (OpenSMTPD) with ESMTP id 0eaf4a6f; Wed, 19 Mar 2025 11:20:29 +0000 (UTC) From: Dominique Martinet Date: Wed, 19 Mar 2025 20:20:15 +0900 Subject: [PATCH v3] 9p/net: fix improper handling of bogus negative read/write replies Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250319-9p_unsigned_rw-v3-1-71327f1503d0@codewreck.org> X-B4-Tracking: v=1; b=H4sIAG+o2mcC/3XM0QrCIBiG4VsZHmfo72zYUfcRMUz/bRLo0HLF2 L3nBp0UHb4ffM9MEkaHiRyrmUTMLrngS4hdRcygfY/U2dIEGNQcAKga24dPrvdo2zhRJjolrZY gNSPlNEbs3HMDz5fSg0v3EF+bn/m6/qUyp5wK1KrhFhgz15MJFqeI5rYPsScrl+FDSCZ480NAI ZRttKq14geN38SyLG9uAfcH8wAAAA== To: Eric Van Hensbergen , Latchesar Ionkov , Christian Schoenebeck Cc: v9fs@lists.linux.dev, linux-kernel@vger.kernel.org, Robert Morris , Dominique Martinet X-Mailer: b4 0.14-dev-87f09 X-Developer-Signature: v=1; a=openpgp-sha256; l=4885; i=asmadeus@codewreck.org; h=from:subject:message-id; bh=3J58Se8XDTl9BlGgRs5d+IlBlOxSoL35kOrUGSCwDcM=; b=owEBbQKS/ZANAwAIAatOm+xqmOZwAcsmYgBn2qh5cq2NDOvwvpzA9OI2dfr364fxm3CO5+gvH nmwNPRPw82JAjMEAAEIAB0WIQT8g9txgG5a3TOhiE6rTpvsapjmcAUCZ9qoeQAKCRCrTpvsapjm cNKWEACW+5TL7uCVj8SEfCusCrPdUEQN9InPwhuUGzxCUuUe0nnhUhuXbBpP9VOv6VhLSorIWzD qvPoimJdsOAeTY/4zczUyRQTXaVZjOnLFseCPvbecRnzTcEibivRetditsH0fpgt4y6MzgwEX5u qFUTgSGdcigUtztDej4X4R0/0CP6qhrw3Qdq4C3YycC9rmQbZvli2j3FCjyrY5ShK3v+IwGiTh6 wDz3fxLz707fEQiz7tdrYbPzi+XX/fcf+II/ZBnaKJqUYYOL8OCVhxYN4FJpTQYRzi8GigTEOT5 rUhhsVMlR3dqWDQQCtLvH36huPjswBOXjD0EP8L7WSSgwo/SKQlHEF/Dt55JdRD/YeCc5O7cWPu qaDOhpz5X+rBB1G5XWZ63OiadfwrRCeva9Jqu5mTQN3r9gdrNFAd0bieEenA7Q8+99p1r+OwF1Y RUUdAoSb0Z6aL4u2v163zM8uVLwAobwLqd+1mgDVL4rdqey6f74BCVfYNIutS4zHgjeZO/n6YOx VKMP+mu9kkRTG6hm7Mf09da9MZPughyZXNw9RMCHT5N6xR+vAQYrg4kyTdrAYR/vpOWKbT3qvN6 tYbely5AXvdWuSa2/sRjJqlv0+3DmbgxLixxA5+/zUf6K06mC0JBtWwMZzIjht3XvPo0qJ4UFy0 BfLSDrI5+CDPbSw== X-Developer-Key: i=asmadeus@codewreck.org; a=openpgp; fpr=B894379F662089525B3FB1B9333F1F391BBBB00A In p9_client_write() and p9_client_read_once(), if the server incorrectly replies with success but a negative write/read count then we would consider written (negative) <=3D rsize (positive) because both variables were signed. Make variables unsigned to avoid this problem. The reproducer linked below now fails with the following error instead of a null pointer deref: 9pnet: bogus RWRITE count (4294967295 > 3) Reported-by: Robert Morris Closes: https://lore.kernel.org/16271.1734448631@26-5-164.dynamic.csail.mit= .edu Signed-off-by: Dominique Martinet Reviewed-by: Christian Schoenebeck --- Changes in v3: - fix bad print formats - Link to v2: https://lore.kernel.org/r/20250317-9p_unsigned_rw-v2-1-9d7a94= a916ae@codewreck.org Changes in v2: - fixed rsize to be u32 instead of size_t - Link to v1: https://lore.kernel.org/r/20241222-9p_unsigned_rw-v1-1-3ea971= d200cb@codewreck.org --- net/9p/client.c | 30 ++++++++++++++++-------------- 1 file changed, 16 insertions(+), 14 deletions(-) diff --git a/net/9p/client.c b/net/9p/client.c index 09f8ced9f8bb..52a5497cfca7 100644 --- a/net/9p/client.c +++ b/net/9p/client.c @@ -1548,7 +1548,8 @@ p9_client_read_once(struct p9_fid *fid, u64 offset, s= truct iov_iter *to, struct p9_client *clnt =3D fid->clnt; struct p9_req_t *req; int count =3D iov_iter_count(to); - int rsize, received, non_zc =3D 0; + u32 rsize, received; + bool non_zc =3D false; char *dataptr; =20 *err =3D 0; @@ -1571,7 +1572,7 @@ p9_client_read_once(struct p9_fid *fid, u64 offset, s= truct iov_iter *to, 0, 11, "dqd", fid->fid, offset, rsize); } else { - non_zc =3D 1; + non_zc =3D true; req =3D p9_client_rpc(clnt, P9_TREAD, "dqd", fid->fid, offset, rsize); } @@ -1592,11 +1593,11 @@ p9_client_read_once(struct p9_fid *fid, u64 offset,= struct iov_iter *to, return 0; } if (rsize < received) { - pr_err("bogus RREAD count (%d > %d)\n", received, rsize); + pr_err("bogus RREAD count (%u > %u)\n", received, rsize); received =3D rsize; } =20 - p9_debug(P9_DEBUG_9P, "<<< RREAD count %d\n", received); + p9_debug(P9_DEBUG_9P, "<<< RREAD count %u\n", received); =20 if (non_zc) { int n =3D copy_to_iter(dataptr, received, to); @@ -1623,9 +1624,9 @@ p9_client_write(struct p9_fid *fid, u64 offset, struc= t iov_iter *from, int *err) *err =3D 0; =20 while (iov_iter_count(from)) { - int count =3D iov_iter_count(from); - int rsize =3D fid->iounit; - int written; + size_t count =3D iov_iter_count(from); + u32 rsize =3D fid->iounit; + u32 written; =20 if (!rsize || rsize > clnt->msize - P9_IOHDRSZ) rsize =3D clnt->msize - P9_IOHDRSZ; @@ -1633,7 +1634,7 @@ p9_client_write(struct p9_fid *fid, u64 offset, struc= t iov_iter *from, int *err) if (count < rsize) rsize =3D count; =20 - p9_debug(P9_DEBUG_9P, ">>> TWRITE fid %d offset %llu count %d (/%d)\n", + p9_debug(P9_DEBUG_9P, ">>> TWRITE fid %d offset %llu count %u (/%zu)\n", fid->fid, offset, rsize, count); =20 /* Don't bother zerocopy for small IO (< 1024) */ @@ -1659,11 +1660,11 @@ p9_client_write(struct p9_fid *fid, u64 offset, str= uct iov_iter *from, int *err) break; } if (rsize < written) { - pr_err("bogus RWRITE count (%d > %d)\n", written, rsize); + pr_err("bogus RWRITE count (%u > %u)\n", written, rsize); written =3D rsize; } =20 - p9_debug(P9_DEBUG_9P, "<<< RWRITE count %d\n", written); + p9_debug(P9_DEBUG_9P, "<<< RWRITE count %u\n", written); =20 p9_req_put(clnt, req); iov_iter_revert(from, count - written - iov_iter_count(from)); @@ -2098,7 +2099,8 @@ EXPORT_SYMBOL_GPL(p9_client_xattrcreate); =20 int p9_client_readdir(struct p9_fid *fid, char *data, u32 count, u64 offse= t) { - int err, rsize, non_zc =3D 0; + int err, non_zc =3D 0; + u32 rsize; struct p9_client *clnt; struct p9_req_t *req; char *dataptr; @@ -2107,7 +2109,7 @@ int p9_client_readdir(struct p9_fid *fid, char *data,= u32 count, u64 offset) =20 iov_iter_kvec(&to, ITER_DEST, &kv, 1, count); =20 - p9_debug(P9_DEBUG_9P, ">>> TREADDIR fid %d offset %llu count %d\n", + p9_debug(P9_DEBUG_9P, ">>> TREADDIR fid %d offset %llu count %u\n", fid->fid, offset, count); =20 clnt =3D fid->clnt; @@ -2142,11 +2144,11 @@ int p9_client_readdir(struct p9_fid *fid, char *dat= a, u32 count, u64 offset) goto free_and_error; } if (rsize < count) { - pr_err("bogus RREADDIR count (%d > %d)\n", count, rsize); + pr_err("bogus RREADDIR count (%u > %u)\n", count, rsize); count =3D rsize; } =20 - p9_debug(P9_DEBUG_9P, "<<< RREADDIR count %d\n", count); + p9_debug(P9_DEBUG_9P, "<<< RREADDIR count %u\n", count); =20 if (non_zc) memmove(data, dataptr, count); --- base-commit: 28e6f0643ff4431aac807e902ff0c8de16b2216d change-id: 20241222-9p_unsigned_rw-03f95da525a0 Best regards, --=20 Dominique Martinet | Asmadeus